QGIS which strategy for multiple presentation of data [closed]

Question

I have a project based on a map and 2 shapefiles (one with lines, the other with points) This project has to be edited with different looks than the working look: QGis2web, Jpeg, .... For both editions, the way points and lines look (Symbology and labels) has to be different from the working configuration. I first used the duplication process of the 2 shapefile layers, and made the necessary presentation modification. It works but it is rather heavy to move from 1 presentation to the other.(check, uncheck several layers, no automatism) I then heard about styles and models, that can also be used for the same objective, but apparently more easy to handle. I also heard (but not fully understand) that, although the underlying data in the attribute tables are unique, those techniques do not only save the presentation (symbology and labels), but also some modification you can do to the attribute data, as for exemple the virtual fields, forms,..., may be save everything that can be modified in the properties of a layer.

Question 1 : In practice, the duplicate and the style methods seems so similar (except the way we invoke them). What are real the differences?

Question 2: I just need to make variation of symbology and labels, and want to keep the attribute layer unique and maintained in one place. (It is likely that I have to create new fields and virtuals fields). Is there another method those discribed?

I use QGIS version 3.16.16 Hanover

Answer 1

Answer 1 : Style are really useful if you use them in combination with theme ( more details here : https://docs.qgis.org/3.16/en/docs/user_manual/introduction/general_tools.html#configuring-map-themes)

For example, I have about a hundred layers in my usual project, so once i setup two different themes (with two style per layer), it's easy to switch them all to one theme or the other, same with maps, I can visually have one theme on the main screen and another on the map composer.

Answer 2 : If you duplicate the same layer, you can edit attributes in both on them as they go back to the same location. With the fields, you can have for example "Rotation 1" for the first layer and "Rotation 2" for the duplicate and put specific values in each.